Blog - Marmaedarticle-listingtag:www.marmaed.uio.no,2017-07-12:/outreach/blogwww.marmaed.uio.no2019-09-12T10:44:29.018Ztag:www.marmaed.uio.no,2019-11-26:/cees/english/outreach/blogs/marine-science/effects-of-offspring-size-variations-on-population.htmlEffects of offspring size variations on population dynamics in cannibalistic species

In a recent study, we investigated the impact of size variations within cohorts and how this may affect the stability of cannibalistic populations. We found that large variations in size of the offspring tend to stabilize the population dynamics.

2019-11-26T16:07:12.846Z2019-11-26T16:07:12.885Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/langangen-2019-offspring-size-fig1.png?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/langangen-2019-offspring-size-fig1.png?vrtx=thumbnailFigure 1: shows the variance in size of pike at age 1. The line indicates the mean decrease over time and the blue and orange dots indicate years above and below the long-term mean respectively.
tag:www.marmaed.uio.no,2019-10-24:/cees/english/outreach/blogs/marine-science/timing-and-the-effect-of-climate-change-on-high-la.htmlMatch-mismatch and the effect of climate warming on fish populations

Climate warming is changing the timing of among others the reproduction for plankton or fish. Predators depend on an abundant prey supply to feed their young and insure that they survive. When the timing of the prey and the predator are not in synchrony the predator young cannot feed and are dying: there is a mismatch.

2019-10-24T14:13:54.788Z2019-10-24T14:13:55.076Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/durant-2019-mmh-projection-fig-1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/durant-2019-mmh-projection-fig-1.jpg?vrtx=thumbnailFigure 1. Using model projection we show that, due to temperature warming, the small marine fish populations in the Polar region, such as the Barents Sea, may collapse due to an asynchrony, a mismatch, with their prey while it will not be the case in the temperate region, such as the Bay of Biscay.
tag:www.marmaed.uio.no,2019-10-09:/cees/english/outreach/blogs/marine-science/management-decisions-related-to-living-resources-a.htmlManagement decisions related to living resources are often based on imperfect statistical models

Conservation efforts and management decisions on the living environment of our planet often rely on imperfect statistical models. Therefore, managers have to brace for the uncertainty associated with the model and study system i.e., set their acceptable risk level, to make some decisions. However, risk estimates themselves can often be biased. In a recent paper published in
Nature communications we demonstrate that one can back-calculate the correct value of risk by combining data fitting with an extensive simulation–estimation procedure.

2019-10-09T06:58:59.968Z2019-10-09T10:47:25.513Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/langangen-2019-manegement-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/langangen-2019-manegement-fig1.jpg?vrtx=thumbnailFigure 1 Illustration of the method used in the study. Panel A illustrates how several data sets simulated from the same “true” parameters (blue dots) can lead to a range of different estimated parameters (green dots). Panel B illustrates how a range of true parameters could have led to the parameters estimated from the data (green dot) and how this could be potentially biased from the real values (red dot). For a more detailed description of the method, we refer the readers to the paper (Ono et al. 2019).
tag:www.marmaed.uio.no,2019-09-20:/cees/english/outreach/blogs/marine-science/calanus-copepods-are-not-necessarily-hiding-at-dep.htmlCalanus copepods are not necessarily hiding at depth in winter

A new pan-arctic study indicates that
Calanus copepods do not necessarily descend deep for diapause in winter; instead, parts of the population remain active. Moreover, the deeper distribution of the larger and more conspicuous
Calanus hyperboreus indicates that predation pressure is a key trigger for diapause at depth. In the central Arctic Ocean where visual predation pressure is lower, copepods might be relieved from the incentive to descend and can remain closer to the surface in winter.

2019-09-20T12:09:07.309Z2019-09-20T12:39:36.465Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/kvile-2019-calanus-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/kvile-2019-calanus-fig1.jpg?vrtx=thumbnailFigure 1. The copepods Calanus glacialis (picture) and Calanus hyperboreus play important roles in the Arctic ecosystem. A new study sheds light on their distribution during diapause in winter. Photo: Kristina Øie Kvile.
tag:www.marmaed.uio.no,2019-09-12:/outreach/blog/food-webs-in-time.htmlA temporal exploration of food webs using biomonitoring data

Since the very first representation of an ecological network (Camerano, 1880), food webs have become an important tool to explore and summarize the trophic interactions between species that coexist in an ecosystem. The architecture of food webs is intimately related to how ecosystems function, and determines the services ecosystems provide. Changes in the structure of food webs may have drastic consequences for the functioning of ecosystems. Yet, our understanding of how food webs vary over time remains unclear.

Accomplishing a complete inventory of species and their interactions requires significant effort, and the diversity and dynamics of nature makes it challenging to follow variability in food webs over time: species come and go, or become more or less abundant.

In this study, we asked the question: How are changes in species composition (presence/absence and abundances) influencing food web structure over time?

Extreme events in the marine environment, like marine heatwaves, are likely at least as important as changes in mean values for causing threats to biodiversity, with impacts on ecosystem services and consequences for human systems. The potential of human and natural systems to adapt to such changes remains unclear, but two recent articles in the high-impact journal
PNAS look closer at the possibilities.

2019-09-05T23:00:00.000Z2019-09-04T12:14:59.416Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/ottersen-2019-extrem-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/ottersen-2019-extrem-fig1.jpg?vrtx=thumbnailFigure 1. Summary of implications for human communities and ocean ecosystems of adaptation approaches that are based on information from the past (left-hand side) versus those that look forward and consider temperature trends (right-hand side). For human systems, there is a higher return for strategies that are responsive to temperature trends, while for ecosystems, increasing ocean temperatures and more surprises may lead to the replacement of specialist species with generalists, and a consequent decrease in biodiversity. Image from Ottersen and Melbourne-Thomas (2019) designed and drawn by Stacey McCormack (University of Tasmania, Hobart, Australia).
tag:www.marmaed.uio.no,2019-08-26:/cees/english/outreach/blogs/marine-science/fish-population-up-and-down-in-the-gulf-of-st-lawr.htmlFish population up-and-down in the Gulf of St Lawrence

Population abundance depends on production of young and survival of adults. Assessing the contribution of young production to population growth and identify the main drivers of its variability may help to identify appropriate stock management measures. What happens when several stocks, belonging to different trophic levels and habitats, as well as having different exploitation histories are sharing the same environment?

2019-08-26T12:58:04.254Z2019-08-26T12:58:06.121Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/durant-2019-gsl-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/durant-2019-gsl-fig1.jpg?vrtx=thumbnailFigure 1. Effect of change in generation time (µ in years) and water temperature anomaly at 150 m (T 150 in °C) on the population growth elasticity to recruitment (erec). The 7 stocks are presented in different colours. We found that there was a general tendency of an increase of the population growth dependency on recruitment with decrease of the generation time (e.g. due to fishing) and increase of temperature (e.g., due to climate warming).
tag:www.marmaed.uio.no,2019-07-12:/cees/english/outreach/blogs/marine-science/what-eat-cod.htmlWhat cod eat

The Atlantic cod is one of the major predator in the Barents Sea estimated to consume over 5 million tonnes of fish in 2017. In a recent paper (Holt
et al. 2019) we explore the diet of this species using a unique dataset encompassing 33 years of cod stomach sampling by Russian and Norwegian scientists. This time-series is the most comprehensive available cod diet dataset to date and is crucial in helping to answer ecologically important questions on what cod eat and why it matters for predator-prey and food-web dynamics in the Barents Sea ecosystem.

2019-07-12T06:06:03.016Z2019-07-12T06:06:03.082Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/holt-durant-2019-what-cod-eat-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/holt-durant-2019-what-cod-eat-fig1.jpg?vrtx=thumbnailFigure 1. Diet of Atlantic cod of different size (cm) presented as percentage of total prey weight per species/species group. Data are coming from 33-year time-series of stomach-content data from 1984 to 2016.
tag:www.marmaed.uio.no,2019-06-14:/outreach/blog/going-to-the-field-as-an-economist.htmlGoing to the field as an Economist

What does it mean when an economist talks about field work? What is experimental economics? How do you do experiments when your sample are humans? If those questions are on your mind then this little text is for you.

2019-06-14T13:05:33.933Z2019-06-14T13:06:33.414Z//www.marmaed.uio.no/outreach/blog/introduction.jpg?vrtx=thumbnail//www.marmaed.uio.no/outreach/blog/introduction.jpg?vrtx=thumbnailPicture 1. Introducing ourselves to the participants.&#160;
tag:www.marmaed.uio.no,2019-04-30:/cees/english/outreach/blogs/marine-science/climate-effects-on-ecosystems-not-only-bottom-up.htmlClimate effects on ecosystems: not only bottom-up

Climate effects on marine ecosystems are often projected as a bottom-up process. That is, the focus of the projections is often: How do changes in physical conditions and biogeochemical processes at lower trophic levels influence living conditions for fish and other organisms at higher trophic levels? However, this view ignores feedbacks between higher and lower trophic levels.

2019-04-30T09:26:30.278Z2019-04-30T09:26:30.289Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/stige-2019-climate-bottom-up-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/stige-2019-climate-bottom-up-fig1.jpg?vrtx=thumbnailFigure 1. A schematic presentation of how climate, as represented by annual sea ice cover, influences the food web in the central and northern Barents Sea. Climate affects the species directly as well as indirectly through predators, competitors and prey.
tag:www.marmaed.uio.no,2019-04-04:/outreach/blog/catastrophic-dynamics-cod-recovery.htmlCatastrophic dynamics limit Atlantic cod recovery

How can two drivers, fishing pressure and climate change, interact in inducing discontinuous dynamics in 20 Atlantic cod stocks? And how can these dynamics affect stocks´ recovery? We are trying to solve this mystery in our new paper
1 published in Proceeding of the Royal Society B!

2019-04-04T15:57:38.399Z2019-04-05T09:30:08.073Z//www.marmaed.uio.no/outreach/blog/img_0741.jpg?vrtx=thumbnail//www.marmaed.uio.no/outreach/blog/img_0741.jpg?vrtx=thumbnailAtlantic cod, picture by Heike Schwermer&#160;
tag:www.marmaed.uio.no,2018-12-04:/cees/english/outreach/blogs/marine-science/spawndistrib.htmlThe role of climate and size in the spawning distribution of cod

Where the fish are spawning is of tremendous importance for the population (
see our post) but also for the industry relying on it, especially since harvesting is often concentrated on fish that aggregate for to spawn. Climate change and harvesting are known to strongly affect the fish population with effect on the spawning location. In a recent paper (Langangen et al.
Global Change Biology) we explore the question: “who is the culprit of spawning location change: Climate or fishing?”

2018-12-04T08:45:48.162Z2018-12-04T08:46:43.425Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/langangen-2018-spawning-distribution-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/langangen-2018-spawning-distribution-fig1.jpg?vrtx=thumbnailFigure 1. indicates the relative size of catch from different spawning grounds along the Norwegian coast. Møre is situated several hundred km farther away from the Barents Sea compared to Lofoten and Finnmark.&#160;
tag:www.marmaed.uio.no,2018-11-26:/outreach/blog/mediterranean-marine-heatwaves-on-the-move.html Mediterranean Marine Heatwaves On the Move

Late last month, the Intergovernmental Panel on Climate Change issued a Special Report on the Impacts of Global Warming of 1.5 ºC
1 above pre-industrial levels (a rather low-emission pathway), triggering a lot of discussions around its origins and impacts on natural and human systems. In this context, it would be interesting to see how the ocean is likely to respond under - what is considered today as - an "optimistic" scenario for greenhouse gas emissions in the future, relative to more severe projections. Particularly for regions vulnerable to climate change (or else "
Hot Spots") like the Mediterranean Sea, such a comparison would be more meaningful to be performed for the anomalous sea surface temperatures rather than the mean temperature evolution. And if you wonder why, let’s dive into the next paragraph.

2018-11-26T00:07:10.728Z2018-11-26T00:07:10.945Z//www.marmaed.uio.no/outreach/blog/image_mhw_med.png?vrtx=thumbnail//www.marmaed.uio.no/outreach/blog/image_mhw_med.png?vrtx=thumbnailtag:www.marmaed.uio.no,2018-08-24:/outreach/blog/research-vessel.htmlOn board a research vessel

Summer often means it is field season for biologists, and time to get your hands dirty! Here I will give my view of what it is like to be on board of a research vessel in the North Sea, participating in a scientific survey of the fish and invertebrates living on the sea floor.

The extensive spawning migration of Northeast Arctic cod was suggested to be counterbalanced by increased early-offspring survival, however we find in a study published in July in
Marine Ecology Progress Series, that early offspring growth should be considered as another factor explaining this long-distance migration.

2018-08-07T11:32:22.143Z2018-08-07T11:32:22.149Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/farber-2018-ipm-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/farber-2018-ipm-fig1.jpg?vrtx=thumbnailFigure 1. Schematic overview of the model. The right side of the figure shows the spawning grounds of Northeast Arctic (NEA) cod (grey shaded area) along the Norwegian coast. Black slice in the pie charts: amount of energy available for reproduction (thus egg numbers) at the respective spawning grounds (maximum amount if spawning would occur in the Barents Sea; full black circle);white slices: migration costs (calculated for a 100 cm large female). With an increase in migration distance, λ declines from λ &#62; 1 to λ &#60; 1 at the spawning grounds south of Lofoten. In order to maintain a stable population with λ = 1we increase or decrease the mean offspring length
tag:www.marmaed.uio.no,2018-06-04:/outreach/blog/from-shapes-to-numbers.htmlFrom shapes to numbers, and back again

Why do organisms have different shapes? The morphology of species is not random, but the result of a long process of evolution and adaptations to the species’ environment and behaviours. Fish show a large diversity in shapes (e.g. flat fish, eel-like, torpedo-shaped), but how to measure such a diversity? In other words, how to compare objectively the shapes of fish found across an ecological gradient? Those are the questions that Caillon and coauthors tried to answer in a study recently published in Ecosphere (DOI
10.1002/ecs2.2220).

2018-06-04T06:38:22.833Z2018-06-04T06:38:22.858Z//www.marmaed.uio.no/outreach/blog/romain-shape0.png?vrtx=thumbnail//www.marmaed.uio.no/outreach/blog/romain-shape0.png?vrtx=thumbnailtag:www.marmaed.uio.no,2018-05-07:/cees/english/outreach/blogs/marine-science/oil-spill.htmlFishing can make fish populations more sensitive to oil spills

Many heavily fished fish stocks are dominated by young and small fish. The reason is simple: the chance to reach old age is small. If the fisheries selectively target large fish, the dominance of young and small fish becomes even larger. Such skewed age and size distributions can make the fish populations more sensitive to detrimental effects of oil spills.

2018-05-07T08:28:09.282Z2018-05-07T08:28:18.133Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/stige-2018-oilspill-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/stige-2018-oilspill-fig1.jpg?vrtx=thumbnailFigure 1. Many old and large fish in the population can make it more robust to detrimental effects of oil spills. The photograph shows 1 m long cod slung across the backs of cod fishermen, February 1915. Photograph by A. B. Wiltse, National Geographic (source: Wikimedia Commons).
tag:www.marmaed.uio.no,2018-04-10:/cees/english/outreach/blogs/marine-science/haddock-spawning.htmlTemporal variability in haddock spawning grounds

Spawning migration is a prevalent phenomenon for the major fish stocks in the Barents Sea. While many of them migrate to the coast of Norway to spawn they are doing so to different areas. We have studied the Northeast Arctic haddock variability in spawning grounds to understand what drives the observed shifts over time.

2018-04-10T09:47:54.319Z2018-04-10T09:48:34.144Zhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/langangen-2018-haddock-spawning-fig1.jpg?vrtx=thumbnailhttps://www.mn.uio.no/cees/english/outreach/blogs/marine-science/langangen-2018-haddock-spawning-fig1.jpg?vrtx=thumbnailFigure 1. shows an overview of the study area. The assumed spawning intensity within season is shown in the lower right corner. The dotted box indicates the area shown in figure 2.
tag:www.marmaed.uio.no,2018-03-27:/outreach/blog/an-ecologist-climbing-the-mountain-of-resource-eco.htmlAn ecologist climbing the mountain of resource economics

Derivatives, Integrals, Optimal Control Theory, Calculus… as an ecologist (and in particular an empirical ecologist) these terms can be frightening. However, we need to face our fears to take a step towards interdisciplinarity!

2018-03-27T12:26:28.699Z2018-03-27T12:26:28.703Z//www.marmaed.uio.no/outreach/blog/camilla_blog2/book-education-graphing-paper-167682.jpg?vrtx=thumbnail//www.marmaed.uio.no/outreach/blog/camilla_blog2/book-education-graphing-paper-167682.jpg?vrtx=thumbnailtag:www.marmaed.uio.no,2018-03-01:/outreach/blog/fish-–-a-unique-resource-with-unique-risks:-the-ro.htmlFish – A unique resource with unique risks: the role of income diversification

Fishing is one of the most physically [1] and economically [2] risky activities one can engage in. According to the Bureau of Labor Statistics of the United States, fishing and related activities has the second highest rate of workplace fatalities (logging is ranked first) [3]. Today however, we will exclusively focus on the economic risks fishers and their communities face and how fish themselves are a unique natural resource.

The festivities of Saint Valentine´s day are upon us, and this coincides with the arrival of the Northeast Arctic cod to the shores of mainland Norway for spawning, a fish close to the heart of Norwegians. This fish is also known as Barents Sea cod, or in Old Norse
skreið, modern Norwegian
skrei. Skrei might be one of the earliest recognised subtypes of cod, but not until the 20
th and 21
st Century have researchers been able to start pinpointing exactly how it is different from other local cod, with the aid of modern sequencing technology.

2018-02-14T19:42:10.790Z2018-02-14T22:23:07.924Z//www.marmaed.uio.no/outreach/blog/cecilia%C2%B4s-valentine-cod/gadus_morhua_blogg.jpg?vrtx=thumbnail//www.marmaed.uio.no/outreach/blog/cecilia%C2%B4s-valentine-cod/gadus_morhua_blogg.jpg?vrtx=thumbnailFigure 1 Atlantic cod,&#160;Gadus&#160;morhua. The species is easy to identify by&#160;the characteristic barble, "overbite" and shape of lateral line.&#160;Other characteristics for identification are for example position and shape of fins, though not shown clearly on photo.&#160;(Photo: Cecilia Helmerson)&#160;
tag:www.marmaed.uio.no,2018-02-02:/cees/english/outreach/blogs/marine-science/apparent-competition.htmlApparent competition

In a study recently published in Ecology we find apparent competition between major zooplankton groups in a large marine ecosystem. Apparent competition is an indirect, negative interaction between two species or species groups mediated by a third species other than their prey.

Understanding the spatio-temporal dynamics of biotic communities (i.e. knowing when and where different species are) is crucial for the management and conservation of ecosystems. We promote the use of an advanced statistical method, called ‘tensor decomposition’, to reveal the spatio-temporal dynamics of species assemblages using the multidimensionality of collected data set (see study by
Frelat et al. 2017).